*“Our bombs are smarter than the average high school student. At least they can find Kuwait.” - A. Whitney Brown*A few days ago I started to think of an easy formula people could use for figuring out the probability that a blast weapon would scatter within a certain distance. Here is what I came up with.

**How the scatter dice work**

- You roll 1D6 in which two sides have a [hit] marker and four sides have an [arrow] for the direction the blast template scatters.

- You roll 2D6 and add the numbers together to see how far the blast template scatters if an [arrow] is rolled.

- Sometimes you can subtract the BS of the shooter from the 2D6 roll.

**Here is what we know**

- 1 out of 3 times the template doesn't scatter at all due to the [hit] marker.

- 2 out of 3 times the template doesn't scatter if the 2D6 roll is less than or equal to your BS.

**So far the formula looks like this**

- P=Probability that blast templates won't scatter

- P = ( 1/3 ) + ( chance that 2D6 - BS = 0 )

- the ( 1 / 3 ) is because one out of three times we roll a [hit] on the scatter dice

**How do you figure out the odds of a 2D6 roll?**

- There are 36 (6*6) different possibilities when rolling 2D6

- Here is a chart that shows how many possibilities there are for each result on a 2D6 Roll

2D6 ROLL --- # Possibilities

2 --- 1

3 --- 2

4 --- 3

5 --- 4

6 --- 5

7 --- 6

8 --- 5

9 --- 4

10 --- 3

11 --- 2

12 --- 1

2D6 ROLL --- # Possibilities

2 --- 1

3 --- 2

4 --- 3

5 --- 4

6 --- 5

7 --- 6

8 --- 5

9 --- 4

10 --- 3

11 --- 2

12 --- 1

**Now what does the formula look like?**

- P=Probability that blast templates won't scatter

- POSS=Number of possibilities 2D6 will be equal to or less than your BS

- P = ( 1/3 ) + ( ( POSS / 36 ) * 2/3 )

**Let's go through some examples**

**What is the probability that a blast template won't scatter, with a BS 4 shooter?**

- There are 6 ways to roll a 4 or less on 2D6, 1 way to roll 2, 2 ways to roll 3, and 3 ways to roll 4.

- So plug in the values and you get

P = ( 1/3 ) + ( ( 6/36 ) * 2/3 ) = 0.44 = 44% chance the template won't scatter

**What is the probability that a blast template will scatter 2 inches or less with a BS 3 shooter?**

- A BS 3 shooter needs to roll a 5 or less on 2D6 to scatter 2 inches or less.

- Thee are 10 ways to roll 5 or less on 2D6, 1 way to roll 2, 2 ways to roll 3, 3 ways to roll 4, and 4 ways to roll 5.

- So plug in the values and you get

P = ( 1/3 ) + ( (10/36) * 2/3 ) = 0.518 = 52% chance the template won't scatter more than 2 inches

**What is the probability that my deep striking Necron lord will scatter 8 inches or less?**

- You need to roll 8 or less on 2D6 to scatter 8 inches or less.

- There are 26 ways to roll 8 or less on 2D6.

- So plug in the values and you get

P = ( 1/3 ) + ( (26/36) * 2/3 ) = 0.814 = 81% chance of not deep striking more than 8 inches

*- I hope this helps everyone, and of course probability for blast template scatter will be in FarseerMobile and FarseerOnline when they are released. Let me know what you think!*

Ok, so now we just need to figure out the probability of the scatter still hitting something.

ReplyDeleteWould it be a percentage of area covered by the small template inside the total area of scatter? The max area would be a 12" radius circle plus half the width of the template minus the BS of the shooter.

Would that be right Robotbeef? I don't think it could be something we can work out to a sure number since the size of the squad would be basically random. Should we even try it?

I must say, I find your articles fascinating. I've used simple math to guessedimate actions but no where near as advance as you.

ReplyDeleteCould you expand on the article showing the % chances of hitting (2d6-bs or hit) or scattering 1,2,3,4 inches.

The reason I ask is that some scatter isn't a problem as the template still covers models and I'd like to know how effective a shot might be even if it scatters.

Hope this makes sense.

Hi there to every body, it’s my first go to see of this web site; this weblog consists of awesome and in fact good stuff for visitors.

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